About 2 months ago I posted on how to use the xinput command (on Ubuntu and derivatives) to disable an input device. This, however, only works until the next time the computer is restarted. In addition, not all distros provide the xinput command; Debian doesn’t, and I haven’t done any research to determine whether this command needs to be installed or if there is a Debian specific alternative. For the time being, the device in which I need this function to work is my Dell E6410 laptop with an Alps pointing stick which is drifting. By default this is enabled alongside the touchpad, so you can use either of these devices, but there is no simple way to disable the touch stick, even if you plug in a USB mouse as I often do.
The answer for when the Xorg display server is used (generally this is the default display server based on X11 for many years, that is now gradually being superseded by Wayland) is to change the configuration settings in a file that is stored in /usr/share/X11/xorg.conf.d/ and in this case the file name to be edited is 40-libinput.conf . In order to effect the disablement, the xinput list command was first used to get the name of the touchpad device, and then this section making use of that name was added to the bottom of the aforementioned file:
Section “InputClass”
Identifier “disable touch stick”
MatchProduct “AlpsPS/2 ALPS DualPoint Stick”
Option “ignore” “on”
EndSection
Identifier “disable touch stick”
MatchProduct “AlpsPS/2 ALPS DualPoint Stick”
Option “ignore” “on”
EndSection
So that section in the file is pretty straightforward. The MatchProduct entry contains the exact device name string that we got from xinput list and the Option specified “ignore” “on” tells the Xorg server to ignore the device and not enable it.
After doing a reboot the touch stick was found to be out of operation and the xinput list command no longer lists this device.
As I noted in my previous post, the flaky touch stick on this laptop has been a significant issue since it will cause the mouse pointer to drift across the screen quite randomly even when an external mouse is in use and possible options to disable the touch stick at a hardware level (there is for example a Bios setting that in theory would disable it with an external mouse connected) have not worked so far. I did not investigate any possibility however of physically disconnecting the device inside the laptop, but I believe this could be quite difficult as the touch stick is physically located between the keyboard keys and thus it is probably at a hardware level integrated into the keyboard itself and therefore could not be unplugged.
Having this option to disable the touch stick is proving extremely useful since the laptop is otherwise in very good condition for its age and with the installation lately of a 160 GB SSD in place of the regular hard drive and the replacement a few years ago of the original battery, with the limited amount of use since then meaning the new battery should still have at least 90% of its life left, if carefully looked after it will keep going for another decade probably.
I am guessing this xorg.conf.d file entry will work with most distros (including Debian) even if xinput command doesn’t work on some.